The Go/NoGo paradigm used in the present study elicited a robust N2 component. An average of 37 Go trials were used to calculate the averaged waveform in both groups whereas for the alcoholic group, 36 (mean) NoGo trials and for the control group, 34 (mean) NoGo trials were used for the purpose of averaging. Figure 3a shows the ERP averaged waveforms, indicating the N2 component at approximately 250-260 ms. for Go and NoGo conditions for the two groups separately. Four midline sites, namely, Fz, FCz, Cz, and Pz are shown. As depicted in the figure, alcoholic and control groups showed maximum amplitude of Go N2 at the FCz location in the fronto-central region (Figure 3a) whereas maximum amplitude of NoGo N2 was observed at the Fz site in the frontal region for both groups. Alcoholics were found to have lower amplitudes of N2 than controls in both Go and NoGo conditions at all electrode sites.
